Pusch dmrs bundling indication for pusch repetitions

ABSTRACT

Aspects are provided that allow a UE to perform DMRS bundling in PUSCH repetitions in response to a configuration from a base station indicating or enabling the UE to perform the DMRS bundling. The UE receives a configuration from a base station indicating to bundle DMRS in repetitions of an uplink data channel transmission for joint channel estimation. The UE determines a DMRS bundling window based on the configuration. The UE transmits the bundled DMRS in the DMRS bundling window. The base station performs the joint channel estimation based on the bundled DMRS. Improved link quality between the UE and base station and signal gains may accordingly result from applying DMRS bundling over multiple repetitions of PUSCH transmissions.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser.No. 63/137,668, entitled “PUSCH DMRS BUNDLING INDICATION FOR PUSCHREPETITIONS” and filed on Jan. 14, 2021, the disclosure of which isexpressly incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure generally relates to communication systems, andmore particularly, to a wireless communication system between a userequipment (UE) and a base station.

Introduction

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable low latency communications (URLLC). Some aspects of 5G NRmay be based on the 4G Long Term Evolution (LTE) standard. There existsa need for further improvements in 5G NR technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a UE. The apparatusreceives a configuration from a base station indicating to bundledemodulation reference signals (DMRS) in repetitions of an uplink datachannel transmission for joint channel estimation. The apparatusdetermines a DMRS bundling window based on the configuration, theapparatus transmits the bundled DMRS in the DMRS bundling window.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus are provided. The apparatus may be a basestation. The apparatus transmits a configuration to a UE indicating tobundle DMRS in repetitions of an uplink data channel transmission forjoint channel estimation. The apparatus receives the bundled DMRS in aDMRS bundling window based on the configuration, and the apparatusperforms the joint channel estimation based on the bundled DMRS.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIG. 2A is a diagram illustrating an example of a first frame, inaccordance with various aspects of the present disclosure.

FIG. 2B is a diagram illustrating an example of DL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 2C is a diagram illustrating an example of a second frame, inaccordance with various aspects of the present disclosure.

FIG. 2D is a diagram illustrating an example of UL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIGS. 4A and 4B are diagrams illustrating examples of DMRS carried inrepetitions of an uplink data channel transmission.

FIG. 5 is a diagram illustrating an example of a chart showing differentrelationships between signal to noise ratios and block error rates fortransport blocks with and without DMRS bundling.

FIG. 6 is a diagram illustrating an example of a DMRS bundling window inrepetitions of an uplink data channel transmission.

FIG. 7 is a diagram illustrating another example of a DMRS bundlingwindow in repetitions of an uplink data channel transmission.

FIG. 8 is a call flow diagram between a UE and a base station.

FIG. 9 is a flowchart of a method of wireless communication at a UE.

FIG. 10 is a flowchart of a method of wireless communication at a basestation.

FIG. 11 is a diagram illustrating an example of a hardwareimplementation for an example apparatus, namely a UE.

FIG. 12 is a diagram illustrating another example of a hardwareimplementation for another example apparatus, namely a base station.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

When a UE transmits data on a physical uplink shared channel (PUSCH),the UE may transmit demodulation reference signals (DMRS) in each slotcarrying the data. For example, when transmitting DMRS on PUSCH, the UEmay transmit DMRS in consecutive slots carrying uplink data repetitionsscheduled by the base station. The base station may process the DMRS toproduce channel estimates for demodulation of the PUSCH. For example,the base station may measure a reference signal receive power (RSRP) ofthe DMRS in symbols of one of the slots, and determine a channel qualityindicator (CQI) based on the RSRP for the DMRS in that particular slot.The base station may similarly measure RSRP and determine CQI from DMRSin other individual slots. Thus, the base station may estimate thechannel using DMRS individually for each slot.

However, in some cases, such processing of DMRSs individually for eachslot may result in channel estimation errors. For example, if the UE islocated at a cell edge, the RSRP of the DMRS may change between slots(e.g., due to interference between the UE and the base station or otherfactors), and thus the CQI which the base station may determineindividually for one slot may be inaccurate for the next slot. As aresult, if the base station performs link adaptation based on anerroneous channel estimation, the communication link quality between thebase station and the UE may be degraded.

To prevent such degradation in link quality based on erroneous channelestimates, DMRS bundling may be applied. In DMRS bundling, when atransmitter (e.g., a UE) transmits DMRS to a receiver (e.g., a basestation) in multiple slots, for instance one of the DMRS in one slot,another one of the DMRS in a next slot, and so forth, the transmittermaintains power consistency and phase continuity between the DMRS. Forexample, to maintain phase continuity between the DMRS, the DMRS may betransmitted using the same modulation and coding scheme (MCS) (e.g.,binary phase shift keying (BPSK) or quadrature phase shift keying(QPSK)), the DMRS may be transmitted in slots using the same duplexingscheme (e.g., time division duplexing (TDD) or frequency divisionduplexing (FDD)), or the DMRS may be transmitted using continuous,allocated time-domain resources. Similarly, to maintain powerconsistency between the DMRS, the DMRS may be transmitted using the sametransmit power. After the receiver receives the bundled DMRS in themultiple slots, the receiver jointly processes the DMRS (e.g., forchannel estimation). For example, the receiver may measure an averageRSRP from the RSRPs of the power-consistent and phase-continuous DMRS inthe multiple slots, and identify CQI from the average RSRP. Thus, thereceiver may jointly process the DMRS across multiple slots. In thisway, the likelihood of erroneous channel estimates due to RSRP changesbetween slots may be reduced (and signal gains may result) due to DMRSbundling.

Thus, improved link quality through joint channel estimation and signalgains may result from applying DMRS bundling over multiple repetitionsof PUSCH transmissions. Therefore, it would be desirable to specify amechanism to enable DMRS bundling or joint channel estimation overmultiple repetitions of PUSCH transmissions (e.g., with consistent DMRStransmit power and phase continuity). To this end, aspects of thepresent disclosure are provided which allow a base station to configureDMRS bundling (and thus enable joint channel estimation), and whichallow a UE to determine the PUSCH transmissions in which DMRS are to bebundled (e.g., a DMRS bundling window) based on the configuration. Forexample, when the base station configures DMRS bundling in repetitionsof PUSCH transmissions, the base station may configure the UE tomaintain power consistency and phase continuity between the DMRS in therepetitions so that, when the base station receives the power-consistentand phase-continuous DMRS, the base station may jointly process the DMRS(e.g., for channel estimation). Moreover, the UE may determine a DMRSbundling window, including a start time corresponding to one of therepetitions (e.g. a first physical or available slot or symbol for aninitial PUSCH repetition/transmission) and an end time corresponding toanother one of the repetitions (e.g. a last physical or available slotor symbol for a last PUSCH repetition/transmission), in which the UE isto maintain the power consistency and phase continuity between the DMRS.As a result, when the base station indicates the UE to bundle DMRS, thebase station may configure the UE to transmit power consistent and phasecontinuous DMRS across multiple PUSCH slots within the determined DMRSbundling window, and when the base station receives bundled DMRS, thebase station may perform joint channel estimation based on the received,power-consistent and phase-continuous DMRS within the DMRS bundlingwindow. In this way, the aforementioned benefits of improved linkquality and signal gains through DMRS bundling may be achieved.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, user equipment(s) (UE) 104, an Evolved Packet Core (EPC)160, and another core network 190 (e.g., a 5G Core (5GC)). The basestations 102 may include macrocells (high power cellular base station)and/or small cells (low power cellular base station). The macrocellsinclude base stations. The small cells include femtocells, picocells,and microcells.

The base stations 102 configured for 4G Long Term Evolution (LTE)(collectively referred to as Evolved Universal Mobile TelecommunicationsSystem (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interfacewith the EPC 160 through first backhaul links 132 (e.g., S1 interface).The base stations 102 configured for 5G New Radio (NR) (collectivelyreferred to as Next Generation RAN (NG-RAN)) may interface with corenetwork 190 through second backhaul links 184. In addition to otherfunctions, the base stations 102 may perform one or more of thefollowing functions: transfer of user data, radio channel ciphering anddeciphering, integrity protection, header compression, mobility controlfunctions (e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, radio access network (RAN) sharing, MultimediaBroadcast Multicast Service (MBMS), subscriber and equipment trace, RANinformation management (RIM), paging, positioning, and delivery ofwarning messages. The base stations 102 may communicate directly orindirectly (e.g., through the EPC 160 or core network 190) with eachother over third backhaul links 134 (e.g., X2 interface). The firstbackhaul links 132, the second backhaul links 184, and the thirdbackhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y megahertz (MHz) (e.g., 5, 10, 15, 100, 400,etc. MHz) bandwidth per carrier allocated in a carrier aggregation of upto a total of Yx MHz (x component carriers) used for transmission ineach direction. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the Institute of Electrical and Electronics Engineers(IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154, e.g., in a 5 gigahertz (GHz) unlicensedfrequency spectrum or the like. When communicating in an unlicensedfrequency spectrum, the STAs 152/AP 150 may perform a clear channelassessment (CCA) prior to communicating in order to determine whetherthe channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same unlicensed frequencyspectrum (e.g., 5 GHz, or the like) as used by the Wi-Fi AP 150. Thesmall cell 102′, employing NR in an unlicensed frequency spectrum, mayboost coverage to and/or increase capacity of the access network.

The electromagnetic spectrum is often subdivided, based onfrequency/wavelength, into various classes, bands, channels, etc. In 5GNR, two initial operating bands have been identified as frequency rangedesignations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). Thefrequencies between FR1 and FR2 are often referred to as mid-bandfrequencies. Although a portion of FR1 is greater than 6 GHz, FR1 isoften referred to (interchangeably) as a “sub-6 GHz” band in variousdocuments and articles. A similar nomenclature issue sometimes occurswith regard to FR2, which is often referred to (interchangeably) as a“millimeter wave” band in documents and articles, despite beingdifferent from the extremely high frequency (EHF) band (30 GHz-300 GHz)which is identified by the International Telecommunications Union (ITU)as a “millimeter wave” band.

With the above aspects in mind, unless specifically stated otherwise, itshould be understood that the term “sub-6 GHz” or the like if usedherein may broadly represent frequencies that may be less than 6 GHz,may be within FR1, or may include mid-band frequencies. Further, unlessspecifically stated otherwise, it should be understood that the term“millimeter wave” or the like if used herein may broadly representfrequencies that may include mid-band frequencies, may be within FR2, ormay be within the EHF band.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include and/or be referred to as an eNB, gNodeB(gNB), or another type of base station. Some base stations, such as gNB180 may operate in a traditional sub 6 GHz spectrum, in millimeter wavefrequencies, and/or near millimeter wave frequencies in communicationwith the UE 104. When the gNB 180 operates in millimeter wave or nearmillimeter wave frequencies, the gNB 180 may be referred to as amillimeter wave base station. The millimeter wave base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the path lossand short range. The base station 180 and the UE 104 may each include aplurality of antennas, such as antenna elements, antenna panels, and/orantenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, an MBMS Gateway 168, a BroadcastMulticast Service Center (BM-SC) 170, and a Packet Data Network (PDN)Gateway 172. The MME 162 may be in communication with a Home SubscriberServer (HSS) 174. The MME 162 is the control node that processes thesignaling between the UEs 104 and the EPC 160. Generally, the MME 162provides bearer and connection management. All user Internet protocol(IP) packets are transferred through the Serving Gateway 166, whichitself is connected to the PDN Gateway 172. The PDN Gateway 172 providesUE IP address allocation as well as other functions. The PDN Gateway 172and the BM-SC 170 are connected to the IP Services 176. The IP Services176 may include the Internet, an intranet, an IP Multimedia Subsystem(IMS), a PS Streaming Service, and/or other IP services. The BM-SC 170may provide functions for MBMS user service provisioning and delivery.The BM-SC 170 may serve as an entry point for content provider MBMStransmission, may be used to authorize and initiate MBMS Bearer Serviceswithin a public land mobile network (PLMN), and may be used to scheduleMBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMStraffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

The core network 190 may include a Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides Quality of Service(QoS) flow and session management. All user IP packets are transferredthrough the UPF 195. The UPF 195 provides UE IP address allocation aswell as other functions. The UPF 195 is connected to the IP Services197. The IP Services 197 may include the Internet, an intranet, an IMS,a Packet Switch (PS) Streaming Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B,eNB, an access point, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), a transmit reception point (TRP), or someother suitable terminology. The base station 102 provides an accesspoint to the EPC 160 or core network 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heartmonitor, etc.). The UE 104 may also be referred to as a station, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology.

Referring again to FIG. 1 , in certain aspects, the UE 104 may include aUE DMRS bundling component 198. The UE DMRS bundling component 198 isconfigured to receive a configuration from a base station indicating tobundle DMRS in repetitions of an uplink data channel transmission forjoint channel estimation, determine a DMRS bundling window based on theconfiguration, and transmit the bundled DMRS in the DMRS bundlingwindow.

Referring again to FIG. 1 , in certain aspects, the base station 102/180may include a BS DMRS bundling component 199. The BS DMRS bundlingcomponent 199 is configured to transmit a configuration to a UEindicating to bundle DMRS in repetitions of an uplink data channeltransmission for joint channel estimation, receive the bundled DMRS in aDMRS bundling window based on the configuration, and perform the jointchannel estimation based on the bundled DMRS.

Although the present disclosure may focus on 5G NR, the concepts andvarious aspects described herein may be applicable to other similarareas, such as LTE, LTE-Advanced (LTE-A), Code Division Multiple Access(CDMA), Global System for Mobile communications (GSM), or otherwireless/radio access technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The NR frame structure may befrequency division duplexed (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplexed (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and F isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

Other wireless communication technologies may have a different framestructure and/or different channels. A frame, e.g., of 10 milliseconds(ms), may be divided into 10 equally sized subframes (1 ms). Eachsubframe may include one or more time slots. Subframes may also includemini-slots, which may include 7, 4, or 2 symbols. Each slot may include7 or 14 symbols, depending on the slot configuration. For slotconfiguration 0, each slot may include 14 symbols, and for slotconfiguration 1, each slot may include 7 symbols. The symbols on DL maybe cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM)(CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for highthroughput scenarios) or discrete Fourier transform (DFT) spread OFDM(DFT-s-OFDM) symbols (also referred to as single carrierfrequency-division multiple access (SC-FDMA) symbols) (for power limitedscenarios; limited to a single stream transmission). The number of slotswithin a subframe is based on the slot configuration and the numerology.For slot configuration 0, different numerologies μ 0 to 4 allow for 1,2, 4, 8, and 16 slots, respectively, per subframe. For slotconfiguration 1, different numerologies 0 to 2 allow for 2, 4, and 8slots, respectively, per subframe. Accordingly, for slot configuration 0and numerology μ, there are 14 symbols/slot and 2^(μ) slots/subframe.The subcarrier spacing and symbol length/duration are a function of thenumerology. The subcarrier spacing may be equal to 2^(μ)*15 kilohertz(kHz), where μ is the numerology 0 to 4. As such, the numerology μ=0 hasa subcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrierspacing of 240 kHz. The symbol length/duration is inversely related tothe subcarrier spacing. FIGS. 2A-2D provide an example of slotconfiguration 0 with 14 symbols per slot and numerology μ=2 with 4 slotsper subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60kHz, and the symbol duration is approximately 16.67 μs. Within a set offrames, there may be one or more different bandwidth parts (BWPs) (seeFIG. 2B) that are frequency division multiplexed. Each BWP may have aparticular numerology.

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R_(x) for one particular configuration, where 100x is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A PDCCH within one BWP may be referred to as a controlresource set (CORESET). Additional BWPs may be located at greater and/orlower frequencies across the channel bandwidth. A primarysynchronization signal (PSS) may be within symbol 2 of particularsubframes of a frame. The PSS is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. A secondarysynchronization signal (SSS) may be within symbol 4 of particularsubframes of a frame. The SSS is used by a UE to determine a physicallayer cell identity group number and radio frame timing. Based on thephysical layer identity and the physical layer cell identity groupnumber, the UE can determine a physical cell identifier (PCI). Based onthe PCI, the UE can determine the locations of the aforementioned DM-RS.The physical broadcast channel (PBCH), which carries a masterinformation block (MIB), may be logically grouped with the PSS and SSSto form a synchronization signal (SS)/PBCH block (also referred to as SSblock (SSB)). The MIB provides a number of RBs in the system bandwidthand a system frame number (SFN). The physical downlink shared channel(PDSCH) carries user data, broadcast system information not transmittedthrough the PBCH such as system information blocks (SIB s), and pagingmessages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit sounding referencesignals (SRS). The SRS may be transmitted in the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The SRS may be used by a base station for channelquality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARQ) acknowledgement (ACK)/non-acknowledgement (NACK)feedback. The PUSCH carries data, and may additionally be used to carrya buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIB s), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIB s) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with UE DMRS bundling component 198 of FIG. 1 .

At least one of the TX processor 316, the RX processor 370, and thecontroller/processor 375 may be configured to perform aspects inconnection with BS DMRS bundling component 199 of FIG. 1 .

When a base station schedules a UE to transmit uplink data in PUSCH, thescheduling may be accomplished using dynamic or configured grants (e.g.,Type-1 configured grants or Type-2 configured grants). When schedulinguplink data in PUSCH in a dynamic grant, the base station may transmit aDCI to the UE including a time domain resource assignment that indicatesparameters associated with the PUSCH transmission, such as a slotoffset, a start and length indicator value (SLIV), and a PUSCH mappingtype (e.g., PUSCH mapping type A or B). The base station may alsotransmit a PUSCH configuration (e.g., pusch-Config or another name) viadedicated RRC signaling to the UE, which may include a time domainallocation list indicating the parameters associated with the timedomain resource assignment in DCI, and a number of repetitions of theuplink data which the UE may transmit on PUSCH in response to the DCI(e.g., in a parameter pusch-AggregationFactor or another name). Whenscheduling uplink data in PUSCH in a Type-1 configured grant (e.g., asemi-statically scheduled grant), the base station may transmit aconfigured grant configuration to the UE (e.g., configuredGrantConfig oranother name) that indicates parameters associated with the PUSCHtransmission, such as an RRC configuration (e.g.,rrc-ConfiguredUplinkGrant or another name) indicating a time domainresource allocation including the slot offset and the SLIV, and a numberof repetitions of the uplink data which the UE may transmit on PUSCH inresponse to the configured grant (e.g., in a parameter repK or anothername). When scheduling uplink data in PUSCH in a Type-2 configured grant(e.g., a semi-persistently scheduled grant), the base station maysimilarly transmit the configured grant configuration to the UE (e.g.,configuredGrantConfig) as described above for Type-1 configured grants,including the number of repetitions (e.g., in parameter repK), butwithout the RRC configuration indicating the time domain resourceallocation (e.g., rrc-ConfiguredUplinkGrant or another name). Instead,the base station indicates the time domain resource allocation to the UEin a DCI which activates the configured grant.

The base station may indicate or configure the number of repetitions viaRRC (e.g., in the PUSCH configuration via parameterpusch-AggregationFactor for dynamically scheduled grants, or in theconfigured grant configuration via parameter repK for Type-1 and Type-2configured grants). Alternatively, the base station may indicate thenumber of repetitions in DCI. For example, the time domain resourceassignment in DCI may indicate the number of repetitions as anadditional parameter associated with the PUSCH transmission.

Furthermore, the repetitions may be configured to be transmitted in thesame symbols of each slot (e.g., PUSCH repetition Type A), or indifferent symbols of each slot (e.g., PUSCH repetition Type B). In PUSCHrepetition Type A, the UE transmits the number of configured repetitionsfor PUSCH using the same symbol allocation in each slot. For example, ifthe base station configures the UE to transmit a same transport block infour repetitions with PUSCH repetition Type A, then the UE may repeatthe transport block across four consecutive slots applying the samesymbol allocation in each slot. Alternatively, in PUSCH repetition TypeB, the UE transmits a number of available repetitions for PUSCH, whichmay be less than the number of configured (or “nominal”) repetitions.For example, if the base station configures the UE to transmit a sametransport block in four repetitions with PUSCH repetition Type B (e.g.,four configured or nominal repetitions), then the UE may repeat thetransport block across up to four consecutive slots in valid (e.g.,uplink) symbols and slots, but the UE may refrain from transmittingrepetitions in invalid (e.g., downlink) symbols and slots. Thus, PUSCHrepetition Type B may be transmitted in different symbols of each slot,since if any of the configured repetitions happen to be scheduled ininvalid symbols not available for the PUSCH transmission (e.g., downlinksymbols), those symbols are excluded from the repetitions.

Additionally, when a UE transmits data on an uplink data channel (e.g.,on PUSCH), the UE may transmit DMRS in each slot carrying the data. Forexample, when transmitting DMRS on PUSCH, the UE may transmit DMRS inconsecutive slots carrying uplink data repetitions scheduled using adynamic grant, a Type-1 configured grant, or a Type-2 configured grantand according to PUSCH repetition Type A or Type B. The base station mayprocess the DMRS to produce channel estimates for demodulation of thePUSCH. For instance, FIG. 4A illustrates an example 400 of multipleslots 402 carrying data in PUSCH including DMRS 404. The datatransmitted in each of the slots 402 may be repetitions of earliertransmitted data (e.g., duplicate transport blocks). For instance, theUE may transmit the same transport block multiple times in order toprovide coverage enhancement if the UE is a significant distance awayfrom the base station. When the base station receives the data in eachof the slots 402, the base station may process the DMRS 404 in each slotindividually for channel estimation. For example, the base station maymeasure a RSRP of the DMRS 404 in symbols 406 of one of the slots 402,and determine a CQI based on the RSRP for the DMRS in that particularslot. The base station may similarly measure RSRP and determine CQI fromDMRS in other individual slots. Thus, the base station may estimate thechannel using DMRS individually for each slot.

However, in some cases, such processing of DMRS individually for eachslot may result in channel estimation errors. For example, if the UE islocated at a cell edge, the RSRP of the DMRS may change between slots(e.g., due to interference between the UE and the base station or otherfactors), and thus the CQI which the base station may determineindividually for one slot may be inaccurate for the next slot. As aresult, if the base station performs link adaptation based on anerroneous channel estimation, the communication link quality between thebase station and the UE may be degraded.

To prevent such degradation in link quality based on erroneous channelestimates, DMRS bundling may be applied. In DMRS bundling, when atransmitter (e.g., a UE) transmits DMRS to a receiver (e.g., a basestation) in multiple slots, for instance one of the DMRS in one slot,another one of the DMRS in a next slot, and so forth, the transmittermaintains phase continuity and power consistency between the DMRS. Forexample, to maintain phase continuity between the DMRS, the DMRS may betransmitted using the same MCS (e.g., BPSK or QPSK), the DMRS may betransmitted in slots using the same duplexing scheme (e.g., TDD or FDD),or the DMRS may be transmitted using continuous, allocated time-domainresources. Similarly, to maintain power consistency between the DMRS orthe DMRS may be transmitted using the same transmit power. After thereceiver receives the bundled DMRS in the multiple slots, the receiverjointly processes the DMRS (e.g., for channel estimation). For example,the receiver may measure an average RSRP from the RSRPs of thepower-consistent and phase-continuous DMRS in the multiple slots, andidentify CQI from the average RSRP. Thus, the receiver may jointlyprocess the DMRS across multiple slots. In this way, the likelihood oferroneous channel estimates due to RSRP changes between slots may bereduced due to DMRS bundling.

For instance, FIG. 4B illustrates an example 450 of multiple slots 452carrying data in PUSCH including bundled DMRS 454. The data transmittedin each of the slots 402 may be repetitions of earlier transmitted data(e.g., duplicate transport blocks). Moreover, the DMRS in each of theslots 452 are power-consistent and phase-continuous (bundled).Accordingly, when the base station receives the data in each of theslots 402, the base station may jointly process the bundled DMRS 454 inthe slots for channel estimation. For example, the base station mayperform joint channel estimation by measuring an average RSRP of theDMRS in symbols 456, 458, and 460 of each of the slots 402, anddetermining a CQI based on the average RSRP for the DMRS in the multipleslots. Thus, the risk of erroneous channel estimation due to RSRPchanges between the slots 452 may be reduced.

In addition to lowering the risk of erroneous channel estimates, DMRSbundling may result in signal gains. FIG. 5 illustrates an example of achart 500 showing signal gains which may occur due to DMRS bundling. Thecurves 502 illustrate block error rates (BLERs) and signal to noiseratios (SNRs) experienced by a UE respectively for slots carrying datafrom same transport blocks (e.g., repetitions of PUSCH transmissionssuch as described above with respect to FIGS. 4A and 4B), and fromdifferent transport blocks (e.g., different PUSCH transmissions). Thisexample also assumes the UE has a single transmitting antenna and fourreceiving antennas, that the UE transmits data including a single DMRSsymbol in a single resource block (RB) or slot to a base station, andthat a frequency shift (Doppler) of 11 Hz exists between the UE and thebase station. As shown in the chart, applying DMRS bundling for jointchannel estimation has been found to result in signal gains ofapproximately 0.8-1.8 dB depending on the number of slots or repetitionsthat include the bundled DMRS.

Thus, FIGS. 4B and 5 illustrate the benefits (e.g., improved linkquality through joint channel estimation and signal gains) which mayresult from applying DMRS bundling over multiple repetitions of PUSCHtransmissions. Moreover, joint channel estimation may be supportedacross repetitions of uplink data scheduled using either a dynamicgrant, a Type-1 configured grant, or a Type-2 configured grant andaccording to either PUSCH repetition Type A or Type B. Therefore, itwould be desirable to specify a mechanism to enable DMRS bundling orjoint channel estimation over multiple repetitions of PUSCHtransmissions (e.g., with consistent DMRS transmit power and phasecontinuity).

To this end, aspects of the present disclosure are provided which allowa base station to configure DMRS bundling (and thus enable joint channelestimation), and which allow a UE to determine the PUSCH transmissionsin which DMRS are to be bundled (e.g., a DMRS bundling window) based onthe configuration. For example, when the base station configures DMRSbundling in repetitions of PUSCH transmissions, the base station mayconfigure the UE to maintain power consistency and phase continuitybetween the DMRS in the repetitions so that, when the base stationreceives the power-consistent and phase-continuous DMRS, the basestation may jointly process the DMRS (e.g., for channel estimation).Moreover, the UE may determine a DMRS bundling window, including a starttime corresponding to one of the repetitions (e.g. a first physical oravailable slot or symbol for an initial PUSCH repetition/transmission)and an end time corresponding to another one of the repetitions (e.g. alast physical or available slot or symbol for a last PUS CHrepetition/transmission), in which the UE is to maintain the powerconsistency and phase continuity between the DMRS. As a result, when thebase station indicates the UE to bundle DMRS, the base station mayconfigure the UE to transmit power consistent and phase continuous DMRSacross multiple PUSCH slots within the determined DMRS bundling window,and when the base station receives bundled DMRS, the base station mayperform joint channel estimation based on the received, power-consistentand phase-continuous DMRS within the DMRS bundling window. In this way,the aforementioned benefits of improved link quality and signal gainsthrough DMRS bundling may be achieved.

Although the following examples to be described with respect to DMRSbundling refer to situations where the PUSCH transmissions occupy thesame frequency (e.g. the same 12 subcarriers of multiple physicalresource blocks without frequency hopping such as illustrated in FIG.4B), the transmissions may alternatively occupy multiple frequencies(e.g. with inter-slot frequency hopping) in other examples. Thus, jointchannel estimation based on DMRS bundling may be performed with orwithout inter-slot frequency hopping. Additionally, although thefollowing examples to be described with respect to DMRS bundling referto PUSCH transmissions occupying a single DMRS bundling window, thetransmissions may alternatively occupy or be split across multiple,consecutive or inconsecutive DMRS bundling windows in other examples.The parameters for each of these multiple DMRS bundling windows, forexample a duration or start/end time for each window, may be configuredin a same or similar manner as for a single DMRS bundling window such asdescribed below.

In a first example, the base station may provide the UE with aconfiguration indicating or enabling the UE to perform DMRS bundling forjoint channel estimation across PUSCH repetitions. For instance, whenthe PUSCH repetitions are dynamically scheduled in DCI, the base stationmay provide the configuration enabling DMRS bundling to the UE withinthe PUSCH configuration (e.g., PUSCH-Config), or within the DCI itself.Alternatively, when the PUSCH repetitions are semi-statically orsemi-persistently scheduled in a configured grant, the base station mayprovide the configuration enabling DMRS bundling to the UE within theconfigured grant configuration (e.g., configuredGrantConfig). Theconfiguration may be, for example, one or more bits or flags indicatingwhether the UE is to bundle DMRS (e.g., maintain power consistency andphase continuity of DMRS) in slots carrying repeated uplink data onPUSCH, so that the base station may perform joint channel estimation onreceived DMRS from the UE. For instance, the configuration may includeone or more bits indicating the UE to transmit the DMRS in each slot ofa PUSCH repetition with the same MCS, with the same TDD or FDD duplexingscheme, in continuous time-domain resources, or with the same transmitpower, for each PUSCH Type A or Type B repetition indicated in the PUSCHconfiguration for dynamically scheduled grants or in the configuredgrant configuration for Type-1 and Type-2 configured grants. Thus, inthis example, the UE may determine the DMRS bundling window to encompassthe indicated number of repetitions (e.g., in the PUSCH configurationvia parameter pusch-AggregationFactor for dynamically scheduled grants,in the configured grant configuration via parameter repK for Type-1 andType-2 configured grants, or in DCI via the time domain resourceassignment), and the base station may perform joint channel estimationof DMRS within the DMRS bundling window.

In a second example, when the base station indicates the number ofrepetitions via an RRC message (e.g., in the PUSCH configuration viaparameter pusch-AggregationFactor for dynamically scheduled grants, inthe configured grant configuration via parameter repK for Type-1 andType-2 configured grants), the UE may determine the DMRS bundling windowto start from the first physical or available slot or symbol carrying aninitial configured PUSCH repetition up to the last physical or availableslot or symbol carrying a final configured PUSCH repetition. Anavailable slot may be a transmission occasion for a PUSCH repetition(e.g., a valid slot or slot including valid symbols, such as an uplinkslot or slot including uplink symbols). A physical slot may be any slot(valid or invalid) for PUSCH repetitions (e.g., a valid or invalid slotor slot including valid or invalid symbols, such as an uplink slot ordownlink slot, or a slot including uplink or downlink symbols). The UEmaintains power consistency and phase continuity in DMRS of adjacentPUSCH transmissions when bundling DMRS within the DMRS bundling window.For instance, FIG. 6 illustrates an example 600 of slots 602 eachincluding DMRS 604 and uplink data on PUSCH 606 which the UE isscheduled to transmit based on a PUSCH configuration or a configuredgrant configuration. Slots 602 may correspond to slots 452 and DMRS 604may correspond to bundled DMRS 454 in FIG. 4B. The base station mayschedule the UE to transmit K PUSCH repetitions via RRC, where Kcorresponds to the number of repetitions indicated in the PUSCHconfiguration or configured grant configuration scheduling the PUSCHtransmissions. For instance, K may be the value 2, 4, 8, or other numberof configured repetitions. When the UE receives the number ofrepetitions K, the UE may determine a DMRS bundling window 608 to have astart time 610 corresponding to a first physical or available slot orsymbol of the initial repetition (Repetition 1) and an end time 612corresponding to a last physical or available slot or symbol of the lastrepetition (Repetition K). Thus, the UE may determine the duration ofthe DMRS bundling window 608 to be K repetitions or slots 602. Upondetermining the DMRS bundling window, the UE may bundle the DMRS 604 inthe slots 602 within the window by transmitting the DMRS in eachconsecutive or adjacent slot with the same MCS, with the same TDD or FDDduplexing scheme, in continuous time-domain resources, or with the sametransmit power in order to maintain power consistency and phasecontinuity between the DMRS. Once the base station receives the bundledDMRS, the base station may perform joint channel estimation (e.g., byidentifying an average RSRP of the DMRS 604 in the slots 602 within DMRSbundling window 608).

In a third example, the UE may be scheduled to transmit the uplink datain PUSCH a number of symbols following reception of the DCI. This numberof symbols may represent a PUSCH preparation procedure time T_(proc,2),where T_(proc,2) is a function of PUSCH preparation time N₂ and a timed_(2,1), where N₂ is based on a numerology p for UE processingcapability 1, where p corresponds to the one of (μ_(DL), μ_(UL))resulting with the largest T_(proc,2) (the smaller value or subcarrierspacing (SCS) between μ_(DL), μ_(UL)), where the μ_(DL) corresponds tothe subcarrier spacing at with the PDCCH carrying the DCI scheduling thePUSCH was transmitted and μ_(UL) corresponds to the subcarrier spacingat which the PUSCH is to be transmitted. For example, the preparationtime N₂ for UE processing capability 1 may be 10, 12, 23, or 36 symbolsdepending on whether the smaller SCS between the SCS associated with theDCI and the SCS associated with the uplink data transmission is 15 kHz(p=0), 30 kHz (p=1), 60 kHz (p=2), or 120 kHz (p=3). Moreover, thenumber of symbols representing PUSCH preparation procedure timeT_(proc,2) assumes that the first symbol of the PUSCH allocationconsists of DMRS only (d2,1=0). Thus, the UE may determine a preparationtime gap of at least 10, 12, 23, or 36 symbols between reception of theDCI and the first DMRS to be transmitted in PUSCH.

Moreover, when the base station dynamically indicates the number ofrepetitions (e.g., via DCI in the time domain resource assignment), theUE may determine the DMRS bundling window to start an additional numberof symbols after the PUSCH preparation procedure time T_(proc,2). Thisadditional number of symbols may represent an additional time gap d,between reception of the DCI and transmission of uplink data on PUSCH ina configured repetition. Thus, the start time of the DMRS bundlingwindow may correspond to a first physical or available slot or symbol ofa first PUSCH repetition scheduled to be transmitted T_(proc,2)+dsymbols after reception of DCI, while the end time of the DMRS bundlingmay window may correspond to a last physical or available slot or symbolof a last configured PUSCH repetition. As in the previous example, theUE maintains power consistency and phase continuity in DMRS of adjacentPUSCH transmissions when bundling DMRS within the DMRS bundling window.In contrast, for DMRS not within the DMRS bundling window (e.g., DMRSthat may be transmitted during the additional time gap d), the UE doesnot actively seek to maintain power consistency and phase continuitybetween those DMRS, since those DMRS are not bundled.

The additional time gap d may be an element of a set of durations (e.g.,d∈{0,1,2} symbols, or a set of some other numbers of symbols), which theUE may determine based on SCS. For example, similar to when calculatingT_(proc,2), the UE may determine the smaller SCS between the SCSassociated with the DCI and the SCS associated with the PUSCHrepetitions, and identify the additional time gap d as either 0, 1, or 2symbols depending on the value of the smaller SCS.

Additionally, the UE may report the additional time gap d which the UEdetermines to apply for its PUSCH repetitions as a UE capability. Forinstance, when the base station sends a UE capability inquiry message tothe UE during initial access or some other time, the UE may report in acapability information message to the base station the additional timegap d that the UE has selected based on SCS (and thus is capable ofapplying for DMRS bundling). For example, the UE may report to the basestation that the UE is capable of applying an additional time gapd∈{0,1,2} symbols between reception of the DCI and the start of the DMRSbundling window. Thus, when the UE transmits its PUSCH repetitionsaccording to the determined additional time gap d, the base station maymonitor for the PUSCH repetitions accordingly based on the capabilityinformation message. For instance, the base station may determine thatbundled DMRS will be received 0, 1, or 2 symbols after T_(proc,2)depending on the value of d indicated in the capability informationmessage.

For instance, FIG. 7 illustrates an example 700 of slots 702 eachincluding DMRS 704 and uplink data on PUSCH 706 which the UE isscheduled to transmit based on a PUSCH configuration or DCI. Slots 702may correspond to slots 452 and DMRS 704 may correspond to bundled DMRS454 in FIG. 4B. The base station may schedule the UE to transmit anumber of PUSCH repetitions via DCI 708 (e.g., 2, 4, 8, or other numberof configured repetitions). When the UE receives the number ofrepetitions in DCI 708, the UE may determine a DMRS bundling window 710,which start time corresponds to a configured PUSCH repetition that isscheduled to occur after a PUSCH preparation time 712 (T_(proc,2)) andan additional time gap 714 (d). The additional time gap 714 may bedetermined based on the smaller SCS between a SCS 716 associated withthe DCI 708 and a SCS 718 associated with the slots 702 including thePUSCH repetitions. The end time of the DMRS bundling window maycorrespond to a last one of the configured PUSCH repetitions. Upondetermining the DMRS bundling window, the UE may bundle the DMRS 704 inthe slots 702 within the window by transmitting the DMRS in eachconsecutive or adjacent slot with the same MCS, with the same TDD or FDDduplexing scheme, in continuous time-domain resources, or with the sametransmit power in order to maintain power consistency and phasecontinuity between the DMRS. Once the base station receives the bundledDMRS, the base station may perform joint channel estimation (e.g., byidentifying an average RSRP of the DMRS 704 in the slots 702 within DMRSbundling window 710).

In a fourth example, the base station may provide the UE a configurationof the DMRS bundling window including a size or duration of the windowand a start time or slot of the window. For example, the base stationmay provide the configuration to the UE within the PUSCH configuration(e.g., PUSCH-Config) for dynamically scheduled grants, within theconfigured grant configuration (e.g., configuredGrantConfig) forsemi-statically or semi-persistently scheduled grants, or within the DCIitself for dynamically scheduled grants. Alternatively, theconfiguration may be separate from the PUSCH configuration, theconfigured grant configuration, or the DCI. The configuration mayexpressly indicate the DMRS bundling window to start from a firstphysical or available slot or symbol of the first configured PUSCHrepetition up to a last physical or available slot or symbol of the lastconfigured PUSCH repetition.

The configuration may also expressly indicate the DMRS bundling windowto start from an nth one of the repetitions up to a last one of therepetitions N, where 1≤n<N. Thus, the configuration may indicate thestart time of the DMRS bundling window as corresponding to any one ofthe PUSCH repetitions scheduled for transmission (except the lastrepetition).

Moreover, the configuration may define the size or duration of the DMRSbundling window as a number of available symbols for PUSCHrepetitions/transmissions (e.g., symbols excluding downlink symbols), oras a number of available slots for PUSCH repetitions/transmissions(e.g., slots excluding downlink slots). For example, if a UE isscheduled to transmit PUSCH repetitions in a sequence of ten slotshaving the following format: DDDUUDDDUU (where D represents a downlinkslot and U represents an uplink slot), the configuration may explicitlyindicate the size of the DMRS bundling window to be four availableslots, since the total number of slots for the PUSCH repetitionsexcluding downlink slots is four. Thus, the UE may determine the DMRSbundling window to be four available slots based on the configuration inthis example.

Alternatively, the configuration may define the size or duration of theDMRS bundling window as a number of physical symbols for PUSCHrepetitions/transmissions (e.g., symbols including uplink and downlinksymbols), a number of physical slots for PUSCH repetitions/transmissions(e.g., slots including uplink and downlink slots), a number ofsubframes, a number of frames, or an amount of time. Thus, the DMRSbundling window may be defined in terms of a total number of symbols,slots, subframes, frames, milliseconds, or some other representation oftime. For example, if a UE is scheduled to transmit PUSCH repetitions ina sequence of ten slots having the following format: DDDUUDDDUU (where Drepresents a downlink slot and U represents an uplink slot), theconfiguration may explicitly indicate the size of the DMRS bundlingwindow to be ten physical slots, ten subframes (assuming 15 kHz SCS),one frame, or 10 ms. Thus, the UE may determine the DMRS bundling windowto be ten physical slots (or ten subframes, one frame, 10 ms, etc.)based on the configuration, even though the UE may actually bundle DMRSin only four of the ten slots (the available or uplink slots).

The UE may indicate a capability of supported DMRS bundling windowsizes. For instance, when the base station sends a UE capability inquirymessage to the UE during initial access or some other time, the UE mayreport in a capability information message to the base station that theUE is capable of performing DMRS bundling (e.g., maintaining powerconsistency and phase continuity) in a specified number of slots,symbols, subframes, frames, or amount of time. The supported DMRSbundling window sizes (e.g., the specified number of slots, symbols, oramount of time) may exclude downlink slots, downlink symbols, ordownlink transmission time. Alternatively, the supported DMRS bundlingwindow sizes may include uplink and downlink slots, uplink and downlinksymbols, or uplink and downlink transmission time. For example, the UEmay inform the base station that the UE is capable of transmitting DMRSin PUSCH repetitions within a DMRS bundling window of four slots(excluding downlink slots) or ten slots (including downlink slots) withthe same MCS, with the same TDD or FDD duplexing scheme, in continuoustime-domain resources, or with the same transmit power. Thus, the basestation may expressly configure the DMRS bundling window in accordancewith the UE's capability.

The base station may indicate the configuration of the DMRS bundlingwindow in system information (e.g., in a SIB), in a medium accesscontrol (MAC) control element (CE), in DCI, or in an RRC message. Afterdetermining the DMRS bundling window start time and duration from theconfiguration, the UE maintains power consistency and phase continuityin DMRS of adjacent PUSCH transmissions when bundling DMRS within theDMRS bundling window. In contrast, for DMRS or for repetitions notwithin the DMRS bundling window, the UE does not actively seek tomaintain power consistency and phase continuity between those DMRS,since those DMRS are not bundled.

FIG. 8 illustrates an example of a call flow 800 between a UE 802 and abase station 804. The UE may transmit a capability information message806 to the base station. The capability information message may indicatea capability of supported DMRS bundling window sizes. The capabilityinformation message may include an additional time gap d, which the UEmay apply between reception of DCI and transmission of uplink data onPUSCH in a configured repetition, that determines the start time of theDMRS bundling window. The capability information message may betransmitted in response to a capability information inquiry from thebase station (e.g., during initial access). For instance, referring tothe third example described above and FIG. 7 , the UE may reportadditional time gap 714 which the UE determines to apply for its PUSCHrepetitions as a UE capability. For instance, the UE may report in acapability information message to the base station the additional timegap d that the UE has selected based on SCS 716, 718 and thus is capableof applying for DMRS bundling.

The base station 804 may provide a DMRS bundling configuration 808 tothe UE 802. For instance, referring to the first example describedabove, the DMRS bundling configuration 808 may be a configurationindicating or enabling the UE to perform DMRS bundling for joint channelestimation across PUSCH repetitions. The configuration may be providedwithin a PUSCH configuration (e.g., PUSCH-Config), within a configuredgrant configuration (e.g., configuredGrantConfig), or within a DCI 810which the base station transmits to the UE. Alternatively, referring tothe fourth example described above, the DMRS bundling configuration 808may be separate from the PUSCH configuration, the configured grantconfiguration, or the DCI 810. In another example, referring to thesecond example described above, the base station may transmit the DMRSbundling configuration 808 to the UE and the number of repetitionsscheduled for PUSCH as different parameters of the PUSCH configurationor the configured grant configuration via RRC. Alternatively, the numberof repetitions may be indicated in DCI 810. For instance, referring tothe third example described above and FIG. 7 , the base station mayprovide DCI 708 to the UE which indicates a number of configured PUSCHrepetitions. In another example, referring to the fourth exampledescribed above, the DMRS bundling configuration 808 may include a sizeor duration of the DMRS bundling window and a start time or slot of thewindow. The DMRS bundling configuration 808 may expressly indicate theDMRS bundling window to start from a first or nth one of the repetitionsup to a last one of the repetitions N, where 1≤n<N. Moreover, the DMRSbundling configuration 808 may define the size or duration of the DMRSbundling window as a number of symbols excluding downlink symbols (e.g.,available symbols), or as a number of slots excluding downlink slots(e.g., available slots). Alternatively, the DMRS bundling configuration808 may define the size or duration of the DMRS bundling window as anumber of symbols including uplink and downlink symbols (e.g., physicalsymbols), a number of slots including uplink and downlink slots (e.g.,physical slots), a number of subframes, a number of frames, or an amountof time. The base station may indicate the DMRS bundling configuration808 to the UE in system information (e.g., in a SIB), in a MAC-CE, inDCI (e.g., DCI 810), or in an RRC message.

After receiving the DMRS bundling configuration 808 and optionally DCI810 from base station 804, at 812, the UE 802 determines a DMRS bundlingwindow based on the DMRS bundling configuration. For instance, referringto the first example described above, after the base station providesthe DMRS bundling configuration indicating the UE to perform DMRSbundling across an indicated number of PUSCH repetitions (e.g., in thePUSCH configuration via parameter pusch-AggregationFactor fordynamically scheduled grants, in the configured grant configuration viaparameter repK for Type-1 and Type-2 configured grants, or in DCI 810via a time domain resource assignment), the UE may determine the DMRSbundling window to encompass the indicated number of repetitions. Inanother example, referring to the second example described above andFIG. 6 , the UE may determine the DMRS bundling window to start from afirst physical or available symbol or slot carrying a first configuredPUSCH repetition up to a last physical or available symbol or slotcarrying the last configured PUSCH repetition. For instance, the UE maydetermine DMRS bundling window 608 to have a start time 610corresponding to the initial repetition (Repetition 1) and an end time612 corresponding to the last repetition (Repetition K). Thus, the UEmay determine the duration of the DMRS bundling window 608 to be Krepetitions or slots 602. In another example, referring to the thirdexample described above and FIG. 7 , the UE may determine the DMRSbundling window to start an additional number of symbols after the PUSCHpreparation procedure time T_(proc,2). Thus, the UE may determine thestart time of the DMRS bundling window to correspond to a configuredPUSCH repetition scheduled to be transmitted T_(proc,2)+d symbols afterreception of DCI, while the end time of the DMRS bundling window maycorrespond to the last available PUSCH repetition (e.g., the lastconfigured repetition according to PUSCH repetition Type A, or the lastavailable repetition excluding invalid symbols or slots according toPUSCH repetition Type B). For instance, the UE may determine a DMRSbundling window 710, which start time corresponds to a configured PUSCHrepetition that is scheduled to occur after a PUSCH preparation time 712(T_(proc,2)) and an additional time gap 714 (d). In an additionalexample, referring to the fourth example described above, the UE maydetermine the DMRS bundling window expressly from the DMRS bundlingconfiguration 808, including the start time and size or duration of theDMRS bundling window. The UE maintains power consistency and phasecontinuity in DMRS of adjacent PUSCH transmissions when bundling DMRSwithin the DMRS bundling window. In contrast, for DMRS or repetitionsnot within the DMRS bundling window, the UE does not actively seek tomaintain power consistency or phase continuity between those DMRS, sincethose DMRSs are not bundled.

At 814, the UE may determine a time gap between reception of DCI and astart time of the DMRS bundling window. The time gap (e.g., additionaltime gap d) may be an element of a set of durations (e.g., d∈{0,1,2}symbols, or a set of some other numbers of symbols), which the UE maydetermine based on SCS. For example, similar to when calculatingT_(proc,2), the UE may determine the smaller SCS between the SCSassociated with the DCI and the SCS associated with the PUSCHrepetitions, and identify the additional time gap d as either 0, 1, or 2symbols depending on the value of the smaller SCS. For instance,referring to the third example described above and with respect to FIG.7 , after the UE receives DCI 810, the UE may determine additional timegap 714 based on a smaller SCS between a SCS 716 associated with the DCI708 and a SCS 718 associated with the slots 702 including the PUSCHrepetitions.

After determining the DMRS bundling window at 812 and optionally thetime gap at 814, the UE 802 may bundle the DMRS in the slots of PUSCHrepetitions. For instance, at 815, the UE may maintain a powerconsistency and a phase continuity between the DMRS. For example,referring to FIGS. 6 and 7 , the UE may bundle the DMRS 604, 704 in theslots 602, 602 within the DMRS bundling window 608, 710 by transmittingthe DMRS in each consecutive or adjacent slot with the same MCS, withthe same TDD or FDD duplexing scheme, in continuous time-domainresources, or with the same transmit power in order to maintain powerconsistency and phase continuity between the DMRS. The UE 802 maytransmit uplink data 816 on PUSCH in repetitions including the bundledDMRS.

Once the base station 804 receives the bundled DMRS, at 818, the basestation may perform joint channel estimation based on the bundled DMRS.For example, referring to FIGS. 6 and 7 , the base station may performjoint channel estimation (e.g., by identifying an average RSRP of theDMRS 604, 704 in the slots 602, 702 within DMRS bundling window 608,710).

FIG. 9 is a flowchart 900 of a method of wireless communication. Themethod may be performed by a UE (e.g., the UE 104, 350, 802; theapparatus 1102). Optional aspects are illustrated in dashed lines. Themethod allows a UE to perform DMRS bundling in PUSCH repetitions inresponse to a configuration from a base station (e.g., the base station102/180, 310, 804) indicating or enabling the UE to perform the DMRSbundling.

At 902, the UE receives a configuration from a base station indicatingto bundle DMRS in repetitions of an uplink data channel transmission forjoint channel estimation. For example, 902 may be performed byconfiguration component 1140. For instance, referring to FIG. 8 , the UE802 may receive DMRS bundling configuration 808 from base station 804.In one example, referring to FIGS. 6-8 , the DMRS bundling configuration808 may be a configuration indicating or enabling the UE 802 to performDMRS bundling for joint channel estimation across PUSCH repetitions(e.g., repetitions of data in PUSCH 606 or 706). The configuration maybe received in a PUSCH configuration, a configured grant configuration,or DCI. For instance, referring to FIG. 8 , the DMRS bundlingconfiguration 808 may be provided within a PUSCH configuration (e.g.,PUSCH-Config), within a configured grant configuration (e.g.,configuredGrantConfig), or within a DCI 810 which the base station 804transmits to the UE 802.

In another example, the configuration may include a start time of a DMRSbundling window and a duration of the DMRS bundling window. Forinstance, referring to FIGS. 6 and 8 , the DMRS bundling configuration808 may include a size or duration of DMRS bundling window 608 and astart time 610 or starting slot 602 of the window. The configuration mayindicate the start time as corresponding to an nth one of therepetitions, where 1≤n<N, and where N is a last one of the repetitions.For instance, referring to FIGS. 6 and 8 , the DMRS bundlingconfiguration 808 may expressly indicate the DMRS bundling window 608 tostart from a first physical or first available slot of a first or nthone of the repetitions (e.g., Repetition 1 of data in PUSCH 606) up to alast physical or last available slot of a last one of the repetitions N(e.g., Repetition K of data in PUSCH 606), where 1≤n<N. Theconfiguration may indicate the duration of the DMRS bundling window as anumber of available symbols for the repetitions (e.g., excludingdownlink symbols) or a number of available slots for the repetitions(e.g., excluding downlink slots). For instance, referring to FIGS. 6 and8 , the DMRS bundling configuration 808 may define the size or durationof the DMRS bundling window 608 as a number of symbols (e.g. symbols456, 458, 460) excluding downlink symbols, or as a number of slots(e.g., slots 452, 602) excluding downlink slots. Alternatively, theconfiguration may indicate the duration of the DMRS bundling window as anumber of physical symbols for the repetitions (e.g., including uplinkand downlink symbols), a number of physical slots for the repetitions(e.g., including uplink and downlink slots), a number of subframes, anumber of frames, or an amount of time. The configuration may bereceived in system information, a MAC-CE, DCI, or a RRC message. Forinstance, referring to FIG. 8 , the base station 804 may indicate theDMRS bundling configuration 808 to the UE 802 in system information(e.g., in a SIB), in a MAC-CE, in DCI (e.g., DCI 810), or in an RRCmessage. The configuration may also be received in response to acapability information message indicating a supported duration for theDMRS bundling window. For instance, when the base station sends a UEcapability inquiry message to the UE during initial access or some othertime, the UE may report in a capability information message to the basestation that the UE is capable of performing DMRS bundling (maintainingpower consistency and phase continuity) in a specified number of slots,symbols, subframes, frames, or amount of time, and the base station mayexpressly configure the DMRS bundling window in accordance with the UE'scapability.

At 904, the UE determines a DMRS bundling window based on theconfiguration. For example, 904 may be performed by bundling windowcomponent 1142. For instance, referring to FIG. 8 , at 812, the UE 802may determine a DMRS bundling window based on the DMRS bundlingconfiguration 808 received from base station 804. As an example of 904,at 906, the UE may determine a start time of the DMRS bundling window ascorresponding to an initial slot (e.g., physical or available) for aninitial configured one of the repetitions and an end time of the DMRSbundling window as corresponding to a last slot (e.g., physical oravailable) for a last one of the repetitions in response to receiving aRRC message indicating a quantity of the repetitions. For example, 906may be performed by bundling window component 1142. For instance,referring to FIG. 6 , in response to receiving an indicated number ofPUSCH repetitions (e.g., in the PUSCH configuration via parameterpusch-AggregationFactor for dynamically scheduled grants, or in theconfigured grant configuration via parameter repK for Type-1 and Type-2configured grants), the UE may determine DMRS bundling window 608 tohave a start time 610 corresponding to the initial repetition(Repetition 1) and an end time 612 corresponding to the last repetition(Repetition K). Thus, the UE may determine the duration of the DMRSbundling window 608 to be K repetitions or slots 602.

At 908, the UE may determine, in response to receiving DCI indicating aquantity of the repetitions, a time gap between reception of the DCI anda start time of the DMRS bundling window. For example, 908 may beperformed by time gap component 1144. For instance, referring to FIGS. 7and 8 , at 814, the UE 802 may determine a time gap (e.g., T_(proc,2)+d)between reception of DCI 708, 810 and a start time of the DMRS bundlingwindow 710. The time gap may comprise a preparation time for the uplinkdata channel transmission (e.g. PUSCH preparation time 712 orT_(proc,2)), and an additional time gap (e.g. additional time gap 714 ord). The additional time gap may be based on a smallest SCS between afirst SCS of the DCI and a second SCS of the uplink data channeltransmission. For example, referring to FIGS. 7 and 8 , after the UE 802receives DCI 708, 810, the UE may determine additional time gap 714based on a smaller SCS between a SCS 716 associated with the DCI 708,810 and a SCS 718 associated with the slots 702 including the PUSCHrepetitions (e.g., the repetitions of data in PUSCH 706).

At 910, the UE may report the additional time gap to the base station ina capability information message. For example, 910 may be performed bycapability information component 1146. For instance, referring to FIGS.7 and 8 , the UE 802 may transmit a capability information message 806to the base station 804 including additional time gap 714 which the UEdetermines to apply for its PUSCH repetitions.

At 909, the UE may maintain a power consistency between the bundledDMRS. For example, 909 may be performed by bundled DMRS component 1148.Similarly, at 911, the UE may maintain a phase continuity between thebundled DMRS. For example, 911 may be performed by bundled DMRScomponent 1148. For instance, referring to FIG. 8 , at 815, the UE 802may maintain power consistency and phase continuity between the DMRS.The UE may maintain power consistency, for example, by applying a sametransmit power to the DMRS in the DMRS bundling window, and the UE maymaintain phase continuity, for example, by applying a same MCS, a sameTDD or FDD scheme, or an allocation in continuous time-domain resourcesto the DMRS in the DMRS bundling window.

Finally, at 912, the UE transmits the bundled DMRS in the DMRS bundlingwindow. For example, 912 may be performed by bundled DMRS component1148. For instance, referring to FIGS. 6-8 , the UE 802 may transmituplink data 816 on PUSCH in repetitions (e.g., the repetitions of datain PUSCH 606, 706) including the bundled DMRS (e.g., DMRS 604, 704).Referring to FIGS. 6 and 7 , the UE may maintain power consistency andphase continuity between the DMRS 604, 704 in the slots 602, 702 withinthe DMRS bundling window 608, 710 by transmitting the DMRS in eachconsecutive or adjacent slot with the same MCS, with the same TDD or FDDduplexing scheme, in continuous time-domain resources, or with the sametransmit power.

FIG. 10 is a flowchart 1000 of a method of wireless communication. Themethod may be performed by a base station (e.g., the base station102/180, 310, 804; the apparatus 1202). Optional aspects are illustratedin dashed lines. The method allows a base station to configure a UE(e.g., the UE 104, 350, 802) to perform DMRS bundling in PUSCHrepetitions to enable the base station to perform joint channelestimation.

At 1002, the base station transmits a configuration to a UE indicatingto bundle DMRS in repetitions of an uplink data channel transmission forjoint channel estimation. For example, 1002 may be performed byconfiguration component 1240. For instance, referring to FIG. 8 , thebase station 804 may transmit DMRS bundling configuration 808 to UE 802.In one example, referring to FIGS. 6-8 , the DMRS bundling configuration808 may be a configuration indicating or enabling the UE 802 to performDMRS bundling for joint channel estimation across PUSCH repetitions(e.g., repetitions of data in PUSCH 606 or 706). The configuration maybe transmitted in a PUSCH configuration, a configured grantconfiguration, or DCI. For instance, referring to FIG. 8 , the DMRSbundling configuration 808 may be provided within a PUSCH configuration(e.g., PUSCH-Config), within a configured grant configuration (e.g.,configuredGrantConfig), or within a DCI 810 which the base station 804transmits to the UE 802.

In another example, the configuration may include a start time of a DMRSbundling window and a duration of the DMRS bundling window. Forinstance, referring to FIGS. 6 and 8 , the DMRS bundling configuration808 may include a size or duration of DMRS bundling window 608 and astart time 610 or starting slot 602 of the window. The configuration mayindicate the start time as corresponding to an nth one of therepetitions, where 1≤n<N, and where N is a last one of the repetitions.For instance, referring to FIGS. 6 and 8 , the DMRS bundlingconfiguration 808 may expressly indicate the DMRS bundling window 608 tostart from a first physical or first available slot of a first or nthone of the repetitions (e.g., Repetition 1 of data in PUSCH 606) up to alast physical or last available slot of a last one of the repetitions N(e.g., Repetition K of data in PUSCH 606), where 1≤n<N. Theconfiguration may indicate the duration of the DMRS bundling window as anumber of available symbols for the repetitions (e.g., excludingdownlink symbols) or a number of available slots for the repetitions(e.g., excluding downlink slots). For instance, referring to FIGS. 6 and8 , the DMRS bundling configuration 808 may define the size or durationof the DMRS bundling window 608 as a number of symbols (e.g. symbols456, 458, 460) excluding downlink symbols, or as a number of slots(e.g., slots 452, 602) excluding downlink slots. Alternatively, theconfiguration may indicate the duration of the DMRS bundling window as anumber of physical symbols for the repetitions (e.g., including uplinkand downlink symbols), a number of physical slots for the repetitions(e.g., including uplink and downlink slots), a number of subframes, anumber of frames, or an amount of time. The configuration may betransmitted in system information, a MAC-CE, DCI, or a RRC message. Forinstance, referring to FIG. 8 , the base station 804 may indicate theDMRS bundling configuration 808 to the UE 802 in system information(e.g., in a SIB), in a MAC-CE, in DCI (e.g., DCI 810), or in an RRCmessage. The configuration may be in response to a capabilityinformation message indicating a supported duration for the DMRSbundling window. For instance, when the base station sends a UEcapability inquiry message to the UE during initial access or some othertime, the UE may report in a capability information message to the basestation that the UE is capable of performing DMRS bundling (maintainingpower consistency and phase continuity) in a specified number of slots,symbols, subframes, frames, or amount of time, and the base station mayexpressly configure the DMRS bundling window in accordance with the UE'scapability.

At 1004, the base station receives the bundled DMRS in a DMRS bundlingwindow based on the configuration. For example, 1004 may be performed bybundled DMRS component 1242. A power consistency may be maintainedbetween the bundled DMRS. Similarly, a phase continuity may bemaintained between the bundled DMRS. For example, the DMRS may have asame MCS, a same TDD or FDD scheme, or an allocation in continuoustime-domain resources for phase continuity, or a same transmit power forpower consistency. For instance, referring to FIGS. 6-8 , in response totransmitting the DMRS bundling configuration 808 to the UE 802, the basestation may receive uplink data 816 on PUSCH in repetitions (e.g.,repetitions of data in PUSCH 606, 706) including the bundled DMRS (e.g.,DMRS 604, 704) within a DMRS bundling window (e.g., DMRS bundling window608, 710). Referring to FIGS. 6 and 7 , the UE may maintain powerconsistency and phase continuity between the DMRS 604, 704 in the slots602, 702 within the DMRS bundling window 608, 710 by transmitting theDMRS in each consecutive or adjacent slot with the same MCS, with thesame TDD or FDD duplexing scheme, in continuous time-domain resources,or with the same transmit power.

In one example, a start time of the DMRS bundling window may correspondto an initial slot (e.g., physical or available) for an initialconfigured one of the repetitions and an end time of the DMRS bundlingwindow may correspond to a last slot (e.g., physical or available) for alast configured one of the repetitions in response to a RRC messageindicating a quantity of the repetitions. For instance, referring toFIG. 6 , in response to receiving an indicated number of PUSCHrepetitions (e.g., in the PUSCH configuration via parameterpusch-AggregationFactor for dynamically scheduled grants, or in theconfigured grant configuration via parameter repK for Type-1 and Type-2configured grants), the UE may determine DMRS bundling window 608 tohave a start time 610 corresponding to the initial repetition(Repetition 1) and an end time 612 corresponding to the last repetition(Repetition K). Thus, the UE may determine the duration of the DMRSbundling window 608 to be K repetitions or slots 602.

In another example, in response to DCI indicating a quantity of therepetitions, the bundled DMRS may be received following a time gapbetween UE reception of the DCI and a start time of the DMRS bundlingwindow. For instance, referring to FIGS. 7 and 8 , at 814, the UE 802may determine a time gap (e.g., T_(proc,2)+d) between reception of DCI708, 810 and a start time of the DMRS bundling window 710. The time gapmay comprise a preparation time for the uplink data channel transmission(e.g. PUSCH preparation time 712 or T_(proc,2)), and an additional timegap (e.g. additional time gap 714 or d). The additional time gap may bebased on a smallest SCS between a first SCS of the DCI and a second SCSof the uplink data channel transmission. For example, referring to FIGS.7 and 8 , after the UE 802 receives DCI 708, 810, the UE may determineadditional time gap 714 based on a smaller SCS between a SCS 716associated with the DCI 708, 810 and a SCS 718 associated with the slots702 including the PUSCH repetitions (e.g., the repetitions of data inPUSCH 706).

At 1006, the base station may receive the additional time gap from theUE in a capability information message. For example, 1006 may beperformed by additional time gap component 1244. For instance, referringto FIGS. 7 and 8 , the UE 802 may transmit a capability informationmessage 806 to the base station 804 including additional time gap 714which the UE determines to apply for its PUSCH repetitions.

Finally, at 1008, the base station performs joint channel estimationbased on the bundled DMRS. For example, 1008 may be performed by jointchannel estimation component 1246. For instance, referring to FIG. 8 ,once the base station 804 receives the bundled DMRS, at 818, the basestation may perform joint channel estimation based on the bundled DMRS.For example, referring to FIGS. 6 and 7 , the base station may performjoint channel estimation by identifying an average RSRP of the DMRS 604,704 in the slots 602, 702 within DMRS bundling window 608, 710, anddetermining a CQI associated with the channel based on the identifiedaverage RSRP.

FIG. 11 is a diagram 1100 illustrating an example of a hardwareimplementation for an apparatus 1102. The apparatus 1102 is a UE andincludes a cellular baseband processor 1104 (also referred to as amodem) coupled to a cellular RF transceiver 1122 and one or moresubscriber identity modules (SIM) cards 1120, an application processor1106 coupled to a secure digital (SD) card 1108 and a screen 1110, aBluetooth module 1112, a wireless local area network (WLAN) module 1114,a Global Positioning System (GPS) module 1116, and a power supply 1118.The cellular baseband processor 1104 communicates through the cellularRF transceiver 1122 with the UE 104 and/or BS 102/180. The cellularbaseband processor 1104 may include a computer-readable medium/memory.The computer-readable medium/memory may be non-transitory. The cellularbaseband processor 1104 is responsible for general processing, includingthe execution of software stored on the computer-readable medium/memory.The software, when executed by the cellular baseband processor 1104,causes the cellular baseband processor 1104 to perform the variousfunctions described supra. The computer-readable medium/memory may alsobe used for storing data that is manipulated by the cellular basebandprocessor 1104 when executing software. The cellular baseband processor1104 further includes a reception component 1130, a communicationmanager 1132, and a transmission component 1134. The communicationmanager 1132 includes the one or more illustrated components. Thecomponents within the communication manager 1132 may be stored in thecomputer-readable medium/memory and/or configured as hardware within thecellular baseband processor 1104. The cellular baseband processor 1104may be a component of the UE 350 and may include the memory 360 and/orat least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359. In one configuration, the apparatus 1102 maybe a modem chip and include just the baseband processor 1104, and inanother configuration, the apparatus 1102 may be the entire UE (e.g.,see 350 of FIG. 3 ) and include the aforediscussed additional modules ofthe apparatus 1102.

The communication manager 1132 includes a configuration component 1140that is configured to receive a configuration from a base stationindicating to bundle DMRS in repetitions of an uplink data channeltransmission for joint channel estimation, e.g., as described inconnection with 902. The communication manager 1132 further includes abundling window component 1142 that receives input in the form of theconfiguration from the configuration component 1140 and is configured todetermine a DMRS bundling window based on the configuration, e.g., asdescribed in connection with 904. For example, the bundling windowcomponent may be configured to determine a start time of the DMRSbundling window as corresponding to an initial slot for an initialconfigured one of the repetitions and an end time of the DMRS bundlingwindow as corresponding to a last slot for a last configured one of therepetitions when a number of the repetitions is indicated in a RRCmessage, e.g., as described in connection with 906. The communicationmanager 1132 further includes a time gap component 1144 that receivesinput in the form of the configuration from the configuration component1140 and is configured to determine, when a number of the repetitions isindicated in DCI, a time gap between reception of the DCI and a starttime of the DMRS bundling window, where the time gap comprises apreparation time for the uplink data channel transmission and anadditional time gap, e.g., as described in connection with 908. Thecommunication manager 1132 further includes a capability informationcomponent 1146 that receives input in the form of the time gap from thetime gap component 1144 and is configured to report the additional timegap to the base station in a capability information message, e.g., asdescribed in connection with 910. The communication manager 1132 furtherincludes a bundled DMRS component 1148 that receives input in the formof the DMRS bundling window from the bundling window component 1142 andis configured to transmit the bundled DMRS in the DMRS bundling window,e.g., as described in connection with 912. The bundled DMRS component1148 may further be configured to maintain a power consistency betweenthe bundled DMRS, e.g., as described in connection with 909, and tomaintain a phase continuity between the bundled DMRS, e.g., as describedin connection with 911.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 9 . Assuch, each block in the aforementioned flowchart of FIG. 9 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

In one configuration, the apparatus 1102, and in particular the cellularbaseband processor 1104, includes means for receiving a configurationfrom a base station indicating to bundle DMRS in repetitions of anuplink data channel transmission for joint channel estimation; means fordetermining a DMRS bundling window based on the configuration; and meansfor transmitting the bundled DMRS in the DMRS bundling window.

In one configuration, the means for determining may be furtherconfigured to determine a start time of the DMRS bundling window ascorresponding to an initial slot for an initial configured one of therepetitions and an end time of the DMRS bundling window as correspondingto a last slot for a last configured one of the repetitions when anumber of the repetitions is indicated in a RRC message.

In one configuration, the means for determining may be furtherconfigured to determine, when a number of the repetitions is indicatedin DCI, a time gap between reception of the DCI and a start time of theDMRS bundling window, wherein the time gap comprises a preparation timefor the uplink data channel transmission and an additional time gap.

In one configuration, the apparatus 1102, and in particular the cellularbaseband processor 1104, may include means for reporting the additionaltime gap to the base station in a capability information message.

In one configuration, the apparatus 1102, and in particular the cellularbaseband processor 1104, may include means for maintaining a powerconsistency between the bundled DMRS and means for maintaining a phasecontinuity between the bundled DMRS.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1102 configured to perform the functionsrecited by the aforementioned means. As described supra, the apparatus1102 may include the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, theaforementioned means may be the TX Processor 368, the RX Processor 356,and the controller/processor 359 configured to perform the functionsrecited by the aforementioned means.

FIG. 12 is a diagram 1200 illustrating an example of a hardwareimplementation for an apparatus 1202. The apparatus 1202 is a BS andincludes a baseband unit 1204. The baseband unit 1204 may communicatethrough a cellular RF transceiver with the UE 104. The baseband unit1204 may include a computer-readable medium/memory. The baseband unit1204 is responsible for general processing, including the execution ofsoftware stored on the computer-readable medium/memory. The software,when executed by the baseband unit 1204, causes the baseband unit 1204to perform the various functions described supra. The computer-readablemedium/memory may also be used for storing data that is manipulated bythe baseband unit 1204 when executing software. The baseband unit 1204further includes a reception component 1230, a communication manager1232, and a transmission component 1234. The communication manager 1232includes the one or more illustrated components. The components withinthe communication manager 1232 may be stored in the computer-readablemedium/memory and/or configured as hardware within the baseband unit1204. The baseband unit 1204 may be a component of the BS 310 and mayinclude the memory 376 and/or at least one of the TX processor 316, theRX processor 370, and the controller/processor 375.

The communication manager 1232 includes a configuration component 1240that is configured to transmit a configuration to a UE indicating tobundle DMRS in repetitions of an uplink data channel transmission forjoint channel estimation, e.g., as described in connection with 1002.The communication manager 1232 further includes a bundled DMRS component1242 that receives input in the form of the configuration from theconfiguration component 1240 and is configured to receive the bundledDMRS in a DMRS bundling window based on the configuration, e.g., asdescribed in connection with 1004. The communication manager 1232further includes an additional time gap component 1244 that isconfigured to receive an additional time gap from the UE in a capabilityinformation message, e.g., as described in connection with 1006. Thecommunication manager 1232 further includes a joint channel estimationcomponent 1246 that receives input in the form of the bundled DMRS fromthe bundled DMRS component 1242 and is configured to perform the jointchannel estimation based on the bundled DMRS, e.g., as described inconnection with 1008.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 10 . Assuch, each block in the aforementioned flowchart of FIG. 10 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

In one configuration, the apparatus 1202, and in particular the basebandunit 1204, includes means for transmitting a configuration to a UEindicating to bundle DMRS in repetitions of an uplink data channeltransmission for joint channel estimation; means for receiving thebundled DMRS in a DMRS bundling window based on the configuration; andmeans for performing the joint channel estimation based on the bundledDMRS

In one configuration, the means for receiving may further be configuredto receive the additional time gap from the UE in a capabilityinformation message.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1202 configured to perform the functionsrecited by the aforementioned means. As described supra, the apparatus1202 may include the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Terms such as “if,” “when,” and“while” should be interpreted to mean “under the condition that” ratherthan imply an immediate temporal relationship or reaction. That is,these phrases, e.g., “when,” do not imply an immediate action inresponse to or during the occurrence of an action, but simply imply thatif a condition is met then an action will occur, but without requiring aspecific or immediate time constraint for the action to occur. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects. Unless specifically stated otherwise, the term “some” refers toone or more. Combinations such as “at least one of A, B, or C,” “one ormore of A, B, or C,” “at least one of A, B, and C,” “one or more of A,B, and C,” and “A, B, C, or any combination thereof” include anycombination of A, B, and/or C, and may include multiples of A, multiplesof B, or multiples of C. Specifically, combinations such as “at leastone of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B,and C,” “one or more of A, B, and C,” and “A, B, C, or any combinationthereof” may be A only, B only, C only, A and B, A and C, B and C, or Aand B and C, where any such combinations may contain one or more memberor members of A, B, or C. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. The words “module,”“mechanism,” “element,” “device,” and the like may not be a substitutefor the word “means.” As such, no claim element is to be construed as ameans plus function unless the element is expressly recited using thephrase “means for.”

The following examples are illustrative only and may be combined withaspects of other embodiments or teachings described herein, withoutlimitation.

Example 1 is a method of wireless communication at a user equipment(UE), comprising: receiving a configuration from a base stationindicating to bundle demodulation reference signals (DMRS) inrepetitions of an uplink data channel transmission for joint channelestimation; determining a DMRS bundling window based on theconfiguration; and transmitting the bundled DMRS in the DMRS bundlingwindow.

Example 2 is the method of Example 1, wherein the configuration isreceived in a physical uplink shared channel (PUSCH) configuration, aconfigured grant configuration, or downlink control information (DCI).

Example 3 is the method of Examples 1 or 2, wherein the determiningcomprises: determining a start time of the DMRS bundling window ascorresponding to an initial slot for an initial configured one of therepetitions and an end time of the DMRS bundling window as correspondingto a last slot for a last configured one of the repetitions in responseto receiving a radio resource control (RRC) message indicating aquantity of the repetitions.

Example 4 is the method of Examples 1 or 2, further comprising:determining, in response to receiving downlink control information (DCI)indicating a quantity of the repetitions, a time gap between receptionof the DCI and a start time of the DMRS bundling window, wherein thetime gap comprises a preparation time for the uplink data channeltransmission and an additional time gap.

Example 5 is the method of Example 4, wherein the additional time gap isbased on a smallest subcarrier spacing (SCS) between a first SCS of theDCI and a second SCS of the uplink data channel transmission.

Example 6 is the method of Examples 4 or 5, further comprising:reporting the additional time gap to the base station in a capabilityinformation message.

Example 7 is the method of any of Examples 1 to 6, wherein theconfiguration includes a start time of the DMRS bundling window and aduration of the DMRS bundling window.

Example 8 is the method of Example 7, wherein the configurationindicates the start time as corresponding to an nth one of therepetitions, wherein 1≤n<N, and wherein N is a last one of therepetitions.

Example 9 is the method of Examples 7 or 8, wherein the configurationindicates the duration of the DMRS bundling window as a number ofavailable symbols for the repetitions or a number of available slots forthe repetitions.

Example 10 is the method of any of Examples 1 to 9, wherein theconfiguration is received in system information, a medium access control(MAC) control element (MAC-CE), downlink control information (DCI), or aradio resource control (RRC) message.

Example 11 is an apparatus for wireless communication, comprising: aprocessor; memory coupled with the processor; and instructions stored inthe memory and operable, when executed by the processor, to cause theapparatus to: receive a configuration from a base station indicating tobundle demodulation reference signals (DMRS) in repetitions of an uplinkdata channel transmission for joint channel estimation; determine a DMRSbundling window based on the configuration; and transmit the bundledDMRS in the DMRS bundling window.

Example 12 is the apparatus of Example 11, wherein the configuration isreceived in a physical uplink shared channel (PUSCH) configuration, aconfigured grant configuration, or downlink control information (DCI).

Example 13 is the apparatus of Examples 11 or 12, wherein theinstructions, when executed by the processor, further cause theapparatus to: determine a start time of the DMRS bundling window ascorresponding to an initial slot for an initial configured one of therepetitions and an end time of the DMRS bundling window as correspondingto a last slot for a last configured one of the repetitions in responseto receiving a radio resource control (RRC) message indicating aquantity of the repetitions.

Example 14 is the apparatus of Examples 11 or 12, wherein theinstructions, when executed by the processor, further cause theapparatus to: determine, in response to receiving downlink controlinformation (DCI) indicating a quantity of the repetitions, a time gapbetween reception of the DCI and a start time of the DMRS bundlingwindow, wherein the time gap comprises a preparation time for the uplinkdata channel transmission and an additional time gap.

Example 15 is the apparatus of Example 14, wherein the additional timegap is based on a smallest subcarrier spacing (SCS) between a first SCSof the DCI and a second SCS of the uplink data channel transmission.

Example 16 is the apparatus of Examples 14 or 15, wherein theinstructions, when executed by the processor, further cause theapparatus to: report the additional time gap to the base station in acapability information message.

Example 17 is the apparatus of any of Examples 11 to 16, wherein theconfiguration includes a start time of the DMRS bundling window and aduration of the DMRS bundling window.

Example 18 is the apparatus of Example 17, wherein the configurationindicates the start time as corresponding to an nth one of therepetitions, wherein 1≤n<N, and wherein N is a last one of therepetitions.

Example 19 is the apparatus of Examples 17 or 18, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of available symbols for the repetitions or a number of availableslots for the repetitions.

Example 20 is the method of any of Examples 11 to 19, wherein theconfiguration is received in system information, a medium access control(MAC) control element (MAC-CE), downlink control information (DCI), or aradio resource control (RRC) message.

Example 21 is an apparatus for wireless communication, comprising: meansfor receiving a configuration from a base station indicating to bundledemodulation reference signals (DMRS) in repetitions of an uplink datachannel transmission for joint channel estimation; means for determininga DMRS bundling window based on the configuration; and means fortransmitting the bundled DMRS in the DMRS bundling window.

Example 22 is the apparatus of Example 21, wherein the configuration isreceived in a physical uplink shared channel (PUSCH) configuration, aconfigured grant configuration, or downlink control information (DCI).

Example 23 is the apparatus of Examples 21 or 22, wherein the means fordetermining is further configured to determine a start time of the DMRSbundling window as corresponding to an initial slot for an initialconfigured one of the repetitions and an end time of the DMRS bundlingwindow as corresponding to a last slot for a last configured one of therepetitions in response to receiving a radio resource control (RRC)message indicating a quantity of the repetitions.

Example 24 is the apparatus of Examples 21 or 22, wherein the means fordetermining is further configured to determine, in response to receivingdownlink control information (DCI) indicating a quantity of therepetitions, a time gap between reception of the DCI and a start time ofthe DMRS bundling window, wherein the time gap comprises a preparationtime for the uplink data channel transmission and an additional timegap.

Example 25 is the apparatus of Example 24, wherein the additional timegap is based on a smallest subcarrier spacing (SCS) between a first SCSof the DCI and a second SCS of the uplink data channel transmission.

Example 26 is the apparatus of Examples 24 or 25, further comprising:means for reporting the additional time gap to the base station in acapability information message.

Example 27 is the apparatus of any of Examples 21 to 26, wherein theconfiguration includes a start time of the DMRS bundling window and aduration of the DMRS bundling window.

Example 28 is the apparatus of Example 27, wherein the configurationindicates the start time as corresponding to an nth one of therepetitions, wherein 1≤n<N, and wherein N is a last one of therepetitions.

Example 29 is the apparatus of Examples 27 or 28, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of available symbols for the repetitions or a number of availableslots for the repetitions.

Example 30 is the apparatus of any of Examples 21 to 29, wherein theconfiguration is received in system information, a medium access control(MAC) control element (MAC-CE), downlink control information (DCI), or aradio resource control (RRC) message.

Example 31 is a computer-readable medium storing computer executablecode, the code when executed by a processor cause the processor to:receive a configuration from a base station indicating to bundledemodulation reference signals (DMRS) in repetitions of an uplink datachannel transmission for joint channel estimation; determine a DMRSbundling window based on the configuration; and transmit the bundledDMRS in the DMRS bundling window.

Example 32 is a method of wireless communication at a base station,comprising: transmitting a configuration to a user equipment (UE)indicating to bundle demodulation reference signals (DMRS) inrepetitions of an uplink data channel transmission for joint channelestimation; receiving the bundled DMRS in a DMRS bundling window basedon the configuration; and performing the joint channel estimation basedon the bundled DMRS.

Example 33 is the method of Example 32, wherein the configuration istransmitted in a physical uplink shared channel (PUSCH) configuration, aconfigured grant configuration, or downlink control information (DCI).

Example 34 is the method of Examples 32 or 33, wherein a start time ofthe DMRS bundling window corresponds to an initial slot for an initialconfigured one of the repetitions and an end time of the DMRS bundlingwindow corresponds to a last slot for a last configured one of therepetitions in response to a radio resource control (RRC) messageindicating a quantity of the repetitions.

Example 35 is the method of Examples 32 or 33, wherein, in response todownlink control information (DCI) indicating a quantity of therepetitions, the bundled DMRS are received following a time gap betweenUE reception of the DCI and a start time of the DMRS bundling window,wherein the time gap comprises a preparation time for the uplink datachannel transmission and an additional time gap.

Example 36 is the method of Example 35, wherein the additional time gapis based on a smallest subcarrier spacing (SCS) between a first SCS ofthe DCI and a second SCS of the uplink data channel transmission.

Example 37 is the method of Examples 35 or 36, further comprising:receiving the additional time gap from the UE in a capabilityinformation message.

Example 38 is the method of any of Examples 32 to 37, wherein theconfiguration includes a start time of the DMRS bundling window and aduration of the DMRS bundling window.

Example 39 is the method of Example 38, wherein the configurationindicates the start time as corresponding to an nth one of therepetitions, wherein 1≤n<N, and wherein N is a last one of therepetitions.

Example 40 is the method of Examples 38 or 39, wherein the configurationindicates the duration of the DMRS bundling window as a number ofavailable symbols for the repetitions or a number of available slots forthe repetitions.

Example 41 is the method of any of Examples 32 to 40, wherein theconfiguration is transmitted in system information, a medium accesscontrol (MAC) control element (MAC-CE), downlink control information(DCI), or a radio resource control (RRC) message.

Example 42 is an apparatus for wireless communication, comprising: aprocessor; memory coupled with the processor; and instructions stored inthe memory and operable, when executed by the processor, to cause theapparatus to: transmit a configuration to a user equipment (UE)indicating to bundle demodulation reference signals (DMRS) inrepetitions of an uplink data channel transmission for joint channelestimation; receive the bundled DMRS in a DMRS bundling window based onthe configuration; and perform the joint channel estimation based on thebundled DMRS.

Example 43 is the apparatus of Example 42, wherein the configuration istransmitted in a physical uplink shared channel (PUSCH) configuration, aconfigured grant configuration, or downlink control information (DCI).

Example 44 is the apparatus of Examples 42 or 43, wherein a start timeof the DMRS bundling window corresponds to an initial slot for aninitial configured one of the repetitions and an end time of the DMRSbundling window corresponds to a last slot for a last configured one ofthe repetitions in response to a radio resource control (RRC) messageindicating a quantity of the repetitions.

Example 45 is the apparatus of Examples 42 or 43, wherein, in responseto downlink control information (DCI) indicating a quantity of therepetitions, the bundled DMRS are received following a time gap betweenUE reception of the DCI and a start time of the DMRS bundling window,wherein the time gap comprises a preparation time for the uplink datachannel transmission and an additional time gap.

Example 46 is the apparatus of Example 45, wherein the additional timegap is based on a smallest subcarrier spacing (SCS) between a first SCSof the DCI and a second SCS of the uplink data channel transmission.

Example 47 is the apparatus of Examples 45 or 46, wherein theinstructions, when executed by the processor, further cause theapparatus to: receive the additional time gap from the UE in acapability information message.

Example 48 is the apparatus of any of Examples 42 to 47, wherein theconfiguration includes a start time of the DMRS bundling window and aduration of the DMRS bundling window.

Example 49 is the apparatus of Example 48, wherein the configurationindicates the start time as corresponding to an nth one of therepetitions, wherein 1≤n<N, and wherein N is a last one of therepetitions.

Example 50 is the apparatus of Examples 48 or 49, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of available symbols for the repetitions or a number of availableslots for the repetitions.

Example 51 is the apparatus of any of Examples 42 to 50, wherein theconfiguration is transmitted in system information, a medium accesscontrol (MAC) control element (MAC-CE), downlink control information(DCI), or a radio resource control (RRC) message.

Example 52 is an apparatus for wireless communication, comprising: meansfor transmitting a configuration to a user equipment (UE) indicating tobundle demodulation reference signals (DMRS) in repetitions of an uplinkdata channel transmission for joint channel estimation; means forreceiving the bundled DMRS in a DMRS bundling window based on theconfiguration; and means for performing the joint channel estimationbased on the bundled DMRS.

Example 53 is the apparatus of Example 52, wherein the configuration istransmitted in a physical uplink shared channel (PUSCH) configuration, aconfigured grant configuration, or downlink control information (DCI).

Example 54 is the apparatus of Examples 52 or 53, wherein a start timeof the DMRS bundling window corresponds to an initial slot for aninitial configured one of the repetitions and an end time of the DMRSbundling window corresponds to a last slot for a last configured one ofthe repetitions in response to a radio resource control (RRC) messageindicating a quantity of the repetitions.

Example 55 is the apparatus of Examples 52 or 53, wherein, in responseto downlink control information (DCI) indicating a quantity of therepetitions, the bundled DMRS are received following a time gap betweenUE reception of the DCI and a start time of the DMRS bundling window,wherein the time gap comprises a preparation time for the uplink datachannel transmission and an additional time gap.

Example 56 is the apparatus of Example 55, wherein the additional timegap is based on a smallest subcarrier spacing (SCS) between a first SCSof the DCI and a second SCS of the uplink data channel transmission.

Example 57 is the apparatus of Examples 55 or 56, wherein the means forreceiving is further configured to receive the additional time gap fromthe UE in a capability information message.

Example 58 is the apparatus of any of Examples 52 to 57, wherein theconfiguration includes a start time of the DMRS bundling window and aduration of the DMRS bundling window.

Example 59 is the apparatus of Example 58, wherein the configurationindicates the start time as corresponding to an nth one of therepetitions, wherein 1≤n<N, and wherein N is a last one of therepetitions.

Example 60 is the apparatus of Examples 58 or 59, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of available symbols for the repetitions or a number of availableslots for the repetitions.

Example 61 is the apparatus of any of Examples 52 to 60, wherein theconfiguration is transmitted in system information, a medium accesscontrol (MAC) control element (MAC-CE), downlink control information(DCI), or a radio resource control (RRC) message.

Example 62 is a computer-readable medium storing computer executablecode, the code when executed by a processor cause the processor to:transmit a configuration to a user equipment (UE) indicating to bundledemodulation reference signals (DMRS) in repetitions of an uplink datachannel transmission for joint channel estimation; receive the bundledDMRS in a DMRS bundling window based on the configuration; and performthe joint channel estimation based on the bundled DMRS.

Example 63 is the method of Examples 7 or 8, wherein the configurationindicates the duration of the DMRS bundling window as a number ofphysical symbols for the repetitions, a number of physical slots for therepetitions, a number of subframes, a number of frames, or an amount oftime.

Example 64 is the method of any of Examples 1 to 10 or 63, wherein theconfiguration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.

Example 65 is the method of any of Examples 1 to 10, 63, or 64, furthercomprising maintaining a power consistency between the bundled DMRS andmaintaining a phase continuity between the bundled DMRS, wherein thebundled DMRS comprises the DMRS having a same modulation and codingscheme (MCS), a same time division duplexing (TDD) or frequency divisionduplexing (FDD) scheme, an allocation in continuous time-domainresources, or a same transmit power.

Example 66 is the apparatus of Examples 17 or 18, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of physical symbols for the repetitions, a number of physicalslots for the repetitions, a number of subframes, a number of frames, oran amount of time.

Example 67 is the apparatus of any of Examples 11 to 19 or 66, whereinthe configuration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.

Example 68 is the apparatus of any of Examples 11 to 19, 66, or 67,wherein the instructions, when executed by the processor, further causethe apparatus to maintain a power consistency between the bundled DMRSand maintain a phase continuity between the bundled DMRS, wherein thebundled DMRS comprises the DMRS having a same modulation and codingscheme (MCS), a same time division duplexing (TDD) or frequency divisionduplexing (FDD) scheme, an allocation in continuous time-domainresources, or a same transmit power.

Example 69 is the apparatus of Examples 27 or 28, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of physical symbols for the repetitions, a number of physicalslots for the repetitions, a number of subframes, a number of frames, oran amount of time.

Example 70 is the apparatus of any of Examples 21 to 29 or 69, whereinthe configuration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.

Example 71 is the apparatus of any of Examples 21 to 29, 69, or 70,further comprising means for maintaining a power consistency between thebundled DMRS and for maintaining maintain a phase continuity between thebundled DMRS, wherein the bundled DMRS comprises the DMRS having a samemodulation and coding scheme (MCS), a same time division duplexing (TDD)or frequency division duplexing (FDD) scheme, an allocation incontinuous time-domain resources, or a same transmit power.

Example 72 is the method of Examples 38 or 39, wherein the configurationindicates the duration of the DMRS bundling window as a number ofphysical symbols for the repetitions, a number of physical slots for therepetitions, a number of subframes, a number of frames, or an amount oftime.

Example 73 is the method of any of Examples 32 to 40 or 72, wherein theconfiguration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.

Example 74 is the method of any of Examples 32 to 40, 72, or 73, whereina power consistency is maintained between the bundled DMRS and a phasecontinuity is maintained between the bundled DMRS, wherein the bundledDMRS comprises the DMRS having a same modulation and coding scheme(MCS), a same time division duplexing (TDD) or frequency divisionduplexing (FDD) scheme, an allocation in continuous time-domainresources, or a same transmit power.

Example 75 is the apparatus of Examples 48 or 49, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of physical symbols for the repetitions, a number of physicalslots for the repetitions, a number of subframes, a number of frames, oran amount of time.

Example 76 is the apparatus of any of Examples 42 to 50 or 75, whereinthe configuration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.

Example 77 is the apparatus of any of Examples 42 to 50, 75 or 76,wherein a power consistency is maintained between the bundled DMRS and aphase continuity is maintained between the bundled DMRS, wherein thebundled DMRS comprises the DMRS having a same modulation and codingscheme (MCS), a same time division duplexing (TDD) or frequency divisionduplexing (FDD) scheme, an allocation in continuous time-domainresources, or a same transmit power.

Example 78 is the apparatus of Examples 58 or 59, wherein theconfiguration indicates the duration of the DMRS bundling window as anumber of physical symbols for the repetitions, a number of physicalslots for the repetitions, a number of subframes, a number of frames, oran amount of time.

Example 79 is the apparatus of any of Examples 52 to 60 or 78, whereinthe configuration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.

Example 80 is the apparatus of any of Examples 52 to 60, 78, or 79,wherein a power consistency is maintained between the bundled DMRS and aphase continuity is maintained between the bundled DMRS, wherein thebundled DMRS comprises the DMRS having a same modulation and codingscheme (MCS), a same time division duplexing (TDD) or frequency divisionduplexing (FDD) scheme, an allocation in continuous time-domainresources, or a same transmit power.

What is claimed is:
 1. A method of wireless communication at a userequipment (UE), comprising: receiving a configuration from a basestation indicating to bundle demodulation reference signals (DMRS) inrepetitions of an uplink data channel transmission for joint channelestimation; determining a DMRS bundling window based on theconfiguration; and transmitting the bundled DMRS in the DMRS bundlingwindow.
 2. The method of claim 1, further comprising: maintaining apower consistency between the bundled DMRS; and maintaining a phasecontinuity between the bundled DMRS.
 3. The method of claim 1, whereinthe configuration is received in a physical uplink shared channel(PUSCH) configuration or a configured grant configuration.
 4. The methodof claim 1, wherein the determining comprises: determining a start timeof the DMRS bundling window as corresponding to an initial slot for aninitial configured one of the repetitions and an end time of the DMRSbundling window as corresponding to a last slot for a last configuredone of the repetitions in response to receiving a radio resource control(RRC) message indicating a quantity of the repetitions.
 5. The method ofclaim 1, wherein the configuration includes a start time of the DMRSbundling window and a duration of the DMRS bundling window.
 6. Themethod of claim 5, wherein the configuration indicates the start time ascorresponding to an nth one of the repetitions, wherein 1≤n<N, andwherein N is a last one of the repetitions.
 7. The method of claim 5,wherein the configuration indicates the duration of the DMRS bundlingwindow as a number of available symbols for the repetitions or a numberof available slots for the repetitions.
 8. The method of claim 5,wherein the configuration indicates the duration of the DMRS bundlingwindow as a number of physical symbols for the repetitions or a numberof physical slots for the repetitions.
 9. The method of claim 5, whereinthe configuration is received in system information, or a radio resourcecontrol (RRC) message.
 10. The method of claim 5, wherein theconfiguration is received in response to a capability informationmessage indicating a supported duration for the DMRS bundling window.11. The method of claim 1, further comprising: determining, in responseto receiving downlink control information (DCI) indicating a quantity ofthe repetitions, a time gap between reception of the DCI and a starttime of the DMRS bundling window, wherein the time gap comprises apreparation time for the uplink data channel transmission and anadditional time gap.
 12. The method of claim 11, wherein the additionaltime gap is based on a smallest subcarrier spacing (SCS) between a firstSCS of the DCI and a second SCS of the uplink data channel transmission.13. The method of claim 11, further comprising: reporting the additionaltime gap to the base station in a capability information message.
 14. Anapparatus for wireless communication, comprising: a processor; memorycoupled with the processor; and instructions stored in the memory andoperable, when executed by the processor, to cause the apparatus to:receive a configuration from a base station indicating to bundledemodulation reference signals (DMRS) in repetitions of an uplink datachannel transmission for joint channel estimation; determine a DMRSbundling window based on the configuration; and transmit the bundledDMRS in the DMRS bundling window.
 15. The apparatus of claim 14, whereinthe instructions, when executed by the processor, further cause theapparatus to: maintain a power consistency between the bundled DMRS; andmaintain a phase continuity between the bundled DMRS.
 16. A method ofwireless communication at a base station, comprising: transmitting aconfiguration to a user equipment (UE) indicating to bundle demodulationreference signals (DMRS) in repetitions of an uplink data channeltransmission for joint channel estimation; receiving the bundled DMRS ina DMRS bundling window based on the configuration; and performing thejoint channel estimation based on the bundled DMRS.
 17. The method ofclaim 16, wherein a power consistency is maintained between the bundledDMRS and a phase continuity is maintained between the bundled DMRS. 18.The method of claim 16, wherein the configuration is transmitted in aphysical uplink shared channel (PUSCH) configuration or a configuredgrant configuration.
 19. The method of claim 16, wherein a start time ofthe DMRS bundling window corresponds to an initial slot for an initialconfigured one of the repetitions and an end time of the DMRS bundlingwindow corresponds to a last slot for a last configured one of therepetitions in response to a radio resource control (RRC) messageindicating a quantity of the repetitions.
 20. The method of claim 16,wherein the configuration includes a start time of the DMRS bundlingwindow and a duration of the DMRS bundling window.
 21. The method ofclaim 20, wherein the configuration indicates the start time ascorresponding to an nth one of the repetitions, wherein 1≤n<N, andwherein N is a last one of the repetitions.
 22. The method of claim 20,wherein the configuration indicates the duration of the DMRS bundlingwindow as a number of available symbols for the repetitions or a numberof available slots for the repetitions.
 23. The method of claim 20,wherein the configuration indicates the duration of the DMRS bundlingwindow as a number of physical symbols for the repetitions or a numberof physical slots for the repetitions.
 24. The method of claim 20,wherein the configuration is transmitted in system information, or aradio resource control (RRC) message.
 25. The method of claim 20,wherein the configuration is received in response to a capabilityinformation message indicating a supported duration for the DMRSbundling window.
 26. The method of claim 16, wherein, in response todownlink control information (DCI) indicating a quantity of therepetitions, the bundled DMRS are received following a time gap betweenUE reception of the DCI and a start time of the DMRS bundling window,wherein the time gap comprises a preparation time for the uplink datachannel transmission and an additional time gap.
 27. The method of claim26, wherein the additional time gap is based on a smallest subcarrierspacing (SCS) between a first SCS of the DCI and a second SCS of theuplink data channel transmission.
 28. The method of claim 26, furthercomprising: receiving the additional time gap from the UE in acapability information message.
 29. An apparatus for wirelesscommunication, comprising: a processor; memory coupled with theprocessor; and instructions stored in the memory and operable, whenexecuted by the processor, to cause the apparatus to: transmit aconfiguration to a user equipment (UE) indicating to bundle demodulationreference signals (DMRS) in repetitions of an uplink data channeltransmission for joint channel estimation; receive the bundled DMRS in aDMRS bundling window based on the configuration; and perform the jointchannel estimation based on the bundled DMRS.
 30. The apparatus of claim29, wherein a power consistency is maintained between the bundled DMRSand a phase continuity is maintained between the bundled DMRS.